Method of treating strip material



? aiented- Benjamin C. McFadden, or to Aluminum Com burgh, Pa.,

Pittsburgh, Pa., assignpany of America, Pittsa corporation of Pennsylvania Application July 8,1939, Serial No. 283,385

This invention relates to a method of treating coils of sheet metal to eliminate surface marring or scratching between adjacent convolutions of a coil of sheet metal particularly during unwinding thereof. 'A

Y It is the present practice to handle sheet metal strip in coils at various stages in the manufacture of metal sheets because of the economy of manufacture effected by coiling and the facility with which such coils canV be handled during subsequent treatment of the metal or storage of the coils. Uncoiling or unwinding of the coils is usually accomplished by loosely supporting a coil in a coil box or cradle, or on a mandrel, and pulling on the tail or free end of the strip. As unwinding progresses, the convolutions or turns of the coil tend to slide or rub on adjacent turns because of the changing shape ofthe coil caused by the pulling force, the weight of the coil, the non-circular form of the coil, etc., thereby tending to cause surface scratching of the metal.

Such scratching or otherwise marring of the surfaces of the metal is particularly undesirable when the metal is to be given a bright rolled or mirror-like nish, and materially adds to the cost of production of finishing sheets since obliteration or removal of surface blemishes entails additional operations that are laborious and expensive. This tendency to scratch during unwinding is aggravated as larger and heavier coils of metal-of increased width are utilized. 4Certain materials are more easily disigured or scratched than others, the softer materials, such as n'on-fencus metals and their. alloys, being particularly susceptible to excessive scratching during unwinding. An important object of the present invention is to provide a method of protecting the contiguous surfaces of sheet metal strip in coiled form during unwinding of the coll so as to obviate the formation of surface blemishes on. said surfaces through changes in the shape of the coil.

Another object of this invention is to provide a method of insulating adjacent convolutions of a coil of sheet metal, whereby to eliminate scratching between contiguous surfaces thereof during uncoiling. I

A further object of the invention is to provide a method of uncoiling sheet metal and simultaneously forming a protecting and lubricating coatingon the surfaces of the metal so as to prevent metal-to-metal contact between adjacent turns of the coils and thereby prevent scratching 'of the metal surfaces through relative movement of the adjacent turns during uncoiling.

A further object is to provide means for effecting the lformation of a film of lubricant between the turns of a coil of sheet metal as the coil is being unwound.

In the accompanying drawing, I show one form of apparatus particularly adapted4 for practicing- `the metal consequently impaired.v Howeverl I i propose to cover the surfaces of the metal with a lm of lubricant whereby the contiguous surfaces of the metal of adjacent convolutions of a coil will be protected by the lubricant nlm, such lubricant forming an insulating layer of lubricant between the turns of the coil which is effective to prevent metal-to-metal contact between adjacent turns during unwinding of the coil.

^ Liquid lubricant may be introduced between the turns of a coil of sheet material by immersing the coil in a hydrocarbon oil bath for a period sufficient to permit the oil to seep between the tlu'ns of the coil and completely coat the surfaces of the metal. The oil bath may be heated if desired in order to expediteseepage of the oil into the spaces between the turns of the coil and thereby reduce the soaking period required to treat the coil.v An an alternative to filling the spaces between adjacent turns of they coil by immersion in an oil bath. oil may be applied byA spraying it against the ends of the coil. In either case the lubricated coil` is moved into unwindig position where lt is supported. for uncoiling in substantially the manner hereinafter described. As the coils are being unwolm the presence of the lm of oil on the surfaces of the metal oi' each turn of the coil eliminates orgreatly minimizes the danger of scratching.

However, in the case of relatively loose or open coils, I prefer to treat each coil of metal with a liquid lubricant as it is being unwound and so I have devised a coil unwinding apparatus-which finds particular adaptation in conjunction with a metal working device such as a rolling mill,

wherein the coils are not only effectively treated to eliminate the danger of known methods and condition of the convolutions scratching but extherebetween,

.art that the mill rolls ation in the manner hereinafter described. It

will be understood, however, that my invention has a wide range of use and is not to be considered as limited to its association with a roll- -iIlEmilL Referring now to the drawing, a pair of working rolls 3 and backing rolls 4 are mounted in the usual way in housings 5 and constitute a four-high rolling mill stand, well known in the art.l VAt the front side of the mill. I provide a coil unwinding device that is adapted to straighten vor flatten and, if desired, feed coiled metal strip into the mill and concurrently therewith appiy a protecting coating of lubricant to the strip. This device comprises a tank 6 that is supported on cross beams 1 carried by a platform 8. Within the tank is disposed a coil supportingcradle 9 which is supported in raised position i relative to the bottom of the tank by blocks I and members II. The cradle 9 is provided with rollers I2 for rotatably supporting metal I3 for free rotary movementthe rollers I2 being arranged in transverse rows with alternate rows staggered relative to adjacent rows, asv shown in Fig. 2, adequately supporting the coil without marking the metal strip. The end of the cradle 9, adjacent to the mill rolls is turned upwardly into arcuate form to embrace the coil I3 and prevent it from being drawn toward the mill. However, the coil I3 may be supported in other ways as by means of a mandrel extending transversely of the tank and axially through the coil.

A pair of pinch rolls I4 are journalled in end plates I5 that are suitably supported in upright position adjacent to the housings 5. The pinch rolls I4 are preferably, positively driven by any suitable source of power to withdraw the strip from the coil I3. After passing the pinch rolls Il the sheet preferably passes between a group of upper and lower flattening or straightening rolls I6A and then passesbetween upper and. lower sets of leveling rolls I1. The two groups of rolls I6-I1 serve to straighten and level the sheet by reversely bending the same during its passage and the sheet enters between the rolls 3 substantiallyfiat. The. rolls Iig-l1 are journalled in the end plates I5 and'it is desira coil of strip so as to form a roller bed for other suitable lubricating liquid to a level above the inside wrap or convolution of the coil Il; and the coil is rotated through the bath by unwinding the outermost turn and passing it to the mill rolls 3. Thus, due to the loose or open condition of the coil, the oil not only seeps and ows into the spaces nominally present between the tunis of the coil, but the relative movements oc-y curring as heretofore described between adjacent turns or coil wraps because of the changing shape of the coil as unwinding progresses facilitate entry and spread of the lubricant over the metal surfaces. This spreading of the lubricant results in coating with lubricant any portion of the adjacent coil wraps coil wraps spread or separate from `each other and form slit-like openings into which the lubricant enters and spreads over the metal surfaces. By reason of the initially loose condition of the coil and the spreading action that takes place between contacting portions of the coil wraps, a heavier'bodied oil or coil treating liquid may be employed advantageously. Such a heavier bodied liquid forms a thicker coating on the surfaces of the metal than will a lighter liquid, and in eifectforms a ller between the adjacent turns of the coil which ller is effective to prevent metalto-metal contact between the turns of th'e coil and thereby prevents scratching of the metal surfaces through repeatedoccurrences of the relative movement of adjacent turns during unwinding. A further advantage of applying liquid to the coil concurrently with rotation` ofthe coil resides in the flushing action of the liquid, wherein foreign matter trapped in the coil is flushed out through surging and slushing of the liquid through the slits opened up between the turns of the coil.

From the foregoing, it will be apparent that, although the coil is only partially immersed in the liquid bath, the loosely wound condition thereof ail'ords rapid entry' of the lubricant between all the coil wraps so that practically the entire surable that the straightening rolls I6 be positively l driven at the same peripheral speed as the pinch rolls I4 until the sheet enters between the rolls '3. Driving power is then preferably so that the rolls II1 serve to tension the sheet as the rolls 3 operate thereon. After passing the work rolls 3, the sheet may be coiled over a ,power-driven coiler indicated generally by the numeral 42l, or may be passed to successive roll stands, slitters, flying shears, or the like, and4 have additional work performed thereon. as desired. It will be apparent to one versed in this 3 may be the only means providedfor drawing the metal from the coil I3, the invention being equally applicable to such an installation.

The tank 6 is discontinued face area of the metal will be coated with lubricant when the entire circumference of the coil has been moved through the bath. An excess amount oflubx'icant entersrthe coil.. and it tends to flow circumferentially between the coil wraps due to rotation of the coil, and thus the lubri-` cant can seep between and coat any surfaces that may be in direct contact. In case the contacting portions do not entirely separate, the pressure therebetween is relieved whereupon spreading of. the lubricant over the contacting surfaces of the metal will be effected by sliding movement therebetween. Hence, the entire surface of the metal will quickly become covered with a protective film of' lubricant. Thereafter, repetitions of such movements in the body of the coil, which ordinarily accumulatively cause surface scratching or marking, take place on a nlm of oil and are practically' rendered harmless. The inner coil wraps which are most likely to become marked Vbecause they are exposed'to a greater number of filled with oil. soap solution. or such movements are adequately protected that may be in surface contact. In addition, under the pull on the str ip,`

bricant to to denitely y and hence, any coils that require prelubrication and have been so lubricated by any of the other described modes of treatment additionally may be beneficially partially immersed and unwound in the foregoing manner, since replenishment of luassures continuous protection for the unwound portion of the coil. The prelubrication of the coils eliminates any possibility of the metal being marked or scratched during the initial stage of unwinding movement as such a prelubricated coil is rotated through the liquid.

the coiled metal surfaces thus affected a pair of wiper biaaes 2a of rubber, feued irabric or other suitable material is disposed in front of the pinch rolls I4 and engage the opposite sides of the uncoiled or withdrawn portion of the sheet to wipe vexcess liquid from the surfaces of the sheet. Suitable squecge'e rolls or brushes may be substituted for the blades 2i. Any entrainedforeign matter harmful 'to the surface finish of the sheet in the subsequent working thereof is carried awayv by the liquid as it is wiped fromthe sheet and returned to the. tank 6. A drip trough 22 is provided beneath the series of rolls I4, i8, and I1 to catch any oil or liquid which may .drip from the rolls and return it to the tank. Any foreign matter in the returned liquid settles at the bottom of the tank and may readily be removed therefrom, or, if desired, the liquid may be ltered and recirculated through the tank 6. It is also possible control the temperature of the liquid within the tank 6 to suit anydesired rolling or operating conditions. The cradle a is disposed above vthe bottom of the tank as heretofore mentioned, so that movement of the coil I3 during unwinding will not materially agitata the sediment in the tank. One of the transverse rows of rollers I2. as indicated in Fig. 1, is adapted to be manually moved vertically into and out of the plane` of the cradle so as to form a stop when in raised position against which a succeeding coil may rest and soak up liquid or oil prior to movement thereof to unwinding position.

.Either before or after transferring the coil to unwinding position, the rotatably supported coil may be manually rotated to atl'ord entry of the liquid lubricant around the entire coil circumference so that the entire surface of the metal may become coated with the lubricant. lsuch preliminary soaking and .rotation of the coils. particularly in the case of wide coils and those that are in a wound condition that inhibits rapid and free infiltration of the liquid between the coil wraps, insures the presence of suillcient lubricant spread over the contiguous surfaces within the coil vto overcome surface marking or scratching during The coils may be treated with variouscom pounds or solutions such as the mineral'lubricating oil mentioned heretofore, or by vegetable oils. soap solutions, or other detergents.

Although I have described a specific embodi- -the scope of the appended claims.

What I claim is:

l. The method of treating a coil of sheet metal to protect the surfaces thereof against scratching by relative movement between adjacent convolutions in the body of the coil during unwinding, which comprises bringing the coil into an intermediate position uid lubricant, maintaining the coil immersed until the seepage of the lubricant between the convolutions of the coil completely covers said sur- ,iaces thereof, then transferring the lubricated position, supporting the coil in coll to unwinding said position ona rotatable surface for free rotary movement, unwinding the coil, and lcontinuously supplying liquid lubricant to the surfaces of the convolutions remaining in the coil until such convolutions in turn are unwound.

2. The method of treating a loose coil of sheet metal to protect the surfaces of adjacent internal wraps of the coil against scratching by relative movement between said surfaces during unwinding of the coil, which comprises bringing the coil into proximity to an yunwinding position, placing the coil on its side in a bath of liquid lubricant at said proximate position to a depth Sui.'-

icient to cover the inner wrap of the coil with lubricant, to permit seepage of the lubricant between all the coil wraps prior'to moving the coil to unwinding position, bath to effect spreading ferentially of the coil, moving the coil to another position in said bath for uncoiling, rotatably supporting thecoil in said other position on'a rotatable surface for unrestrained rotation, and uncoiling the coil.

3. The method of treating a coilof sheet metal to protect thesurfaces thereof against scratching by relative movement between adjacent convolutions in the body of the coil during unwindwhich comprises preliminary to moving it inundatingl .the coil with period suillcient to permit the lubricant to infiltrate into the coil and com-- pletely coat said surfaces, then moving the lubricated coll into unwinding position, rotatably supunwinding the coil 'BmsJAmN c. Mcr'a'nnmr.

preliminary to moving it `into unwinding position, immersing the coll in a liqrotating the coil in said of the lubricant circum- 

